Genetics Probability

In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short? a. 1 b. 1/2 c. 1/4 d. 0

0

Pea flowers may be purple (P) or white (p). Pea seeds may be round (R) or wrinkled (r). What proportion of the offspring from the cross PpRr x PpRr will have white flowers and wrinkled seeds? a. 0 b. 1/16 c. ¼ d. ¾ e. ½

1/16

Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails? a. 1/16 b. 3/16 c. 3/8 d. ½ e. 9/16

1/2

If a heterozygous plant is allowed to self-pollinate, what proportion of the offspring will also be heterozygous? a. 1/4 b. 1/3 c. 1/2 d. 2/3 e. all of them

1/2

Michelle and Keith are apparently normal, but their daughter was born with alkaptonuria, an inherited metabolic disorder. If alkaptonuria is like most other human hereditary disorders, the probability of their next child being born with alkaptonuria is _____. a. 0 b. 1/4 c. 1/2 d. 2/3 e. 3/4

1/4

An AABbccDdEeFF individual is crossed with an individual with the genotype AaBBCCDdEeff. What is the probability that their offspring will have the genotype AaBBCcddEEFf? a. 1/2 b. 1/4 c. 1/16 d. 1/32 e. 1/64

1/64

In the cross AaBbCc × AaBbCc, what is the probability of producing the genotype AABBCC? a. 1/4 b. 1/8 c. 1/16 d. 1/32 e. 1/64

1/64

If each parent can produce 100 genetically distinct gametes, how many genetically distinct offspring can two parents produce? a. 10,000 b. 200 c. 1,000 d. 100 e. 1,000,000

10,000

Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F1 individuals have red, axial flowers. The genes for flower color and location assort independently. If 1,000 F2 offspring resulted from the cross, approximately how many of them would you expect to have red, terminal flowers? a. 65 b. 190 c. 250 d. 565 e. 750

190

Tom's brother suffers from phenylketonuria (PKU), a recessive disorder. The brothers' parents do not have PKU. What are the chances that Tom, who is normal for this trait, is a carrier of PKU? a. 1/4 b. 1/3 c. 1/2 d. 2/3 e. 4/3

2/3

Flower color in snapdragons is an example of incomplete dominance. When a red-flowered plant is crossed with a white-flowered plant, the F1 generation has pink flowers. If a pink-flowered plant is crossed with another pink-flowered plant, the progeny plants will be _____. a. 100% pink b. 100% red c. 25% red, 50% pink, and 25% white d. 50% pink and 50% red e. 25% white and 75% red

25% red, 50% pink, 25% white

Drosophila (fruit flies) usually have long wings, but mutations in the BT gene can result in bent wings and mutations in the VG gene can result in vestigial wings. If flies that are heterozygous for both the bent wing gene and the vestigial wing gene are mated, what is the probability of offspring with bent wings only? Note that the mutant alleles of both genes are recessive. a. 1/8 b. 3/8 c. 1/4 d. 9/16 e. 3/16

3/16

Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F1 individuals have red, axial flowers. The genes for flower color and location assort independently. Among the F2 offspring, what is the probability of plants with white axial flowers? a. 9/16 b. 1/16 c. 3/16 d. 1/8

3/16

Given the parents AABBCc × AabbCc, assume simple dominance for each trait and independent assortment. What proportion of the progeny will be expected to phenotypically resemble the first parent? a. 1/4 b. 1/8 c. ¾ d. 3/8 e. 1

3/4

An individual with the genotype AABbCcDD can make how many different kinds of gametes? a. 2 b. 4 c. 8 d. 16 e. 32

4

Human blood groups are governed by three alleles, A, B, and O. A and B are codominant and O is recessive to both. If a woman with type O blood is expecting a child. Her husband is type A. Both the woman's father and her husband's father had type B blood. What is the probability that the child will have type O blood? a. 100% b. 75% c. 50% d. 25% e. 0%

50%

When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype? a. 0% b. 25% c. 50% d. 75% e. 100%

50%

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant characteristic. If true-breeding red long radishes are crossed with true-breeding white oval radishes, which of the following phenotypic ratios would be expected in the F2 generation? a. 9:3:3:1 b. 9:4:3 c. 1:1:1:1 d. 1:1:1:1:1:1 e. 6:3:3:2:1:1

6:3:3:2:1:1

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE? a. 4 b. 8 c. 16 d. 32

8

Human blood groups are governed by three alleles, A, B, and O. A and B are codominant and O is recessive to both. A man who has type B blood and a woman who has type A blood could have children of which of the following phenotypes? a. A or B only b. AB only c. AB or O d. A, B, or O e. A, B, AB, or O

A, B, AB, or O

A = big apples; R = red apples; a = small apples; r = yellow apples. You have one tree that produces big yellow apples and another tree that produces small red apples. When the two are crossed, you find that half of the new trees produce big red apples and half produce big yellow apples. What are the genotypes of the parents? a. AArr and aaRr b. Aarr and aaRr c. AARr and Aarr d. AaRr and AaRr e. AaRr and aarr

AArr and aaRr

In a certain plant, the alleles A, B, and C are completely dominant to the alleles a, b, and c. A plant with the genotype AABbcc will have the same phenotype as a plant with the genotype _____. a. Aabbcc b. aabbcc c. AaBBcc d. AABBCc e. None of the listed responses is correct.

AaBBcc

The progeny of a cross between two individuals of the "parental generation" are known as a. the F1 generation. b. the F2 generation. c. heterozygotes. d. dihybrids.

F1 generation

A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism? a. tt b. Hh c. HhTt d. HT

HT

Human blood groups are governed by three alleles, A, B, and O. A and B are codominant and O is recessive to both. Which of the following matings cannot produce a child with blood type O? The letters refer to blood types (phenotypes). a. A x A b. A x B c. O x AB d. O x O e. None of the listed responses is correct.

O x AB

Drosophila (fruit flies) usually have long wings, but mutations in the BT gene can result in bent wings and mutations in the VG gene can result in vestigial wings. If a homozygous bent wing fly is mated with a homozygous vestigial wing fly, which of the following offspring would you expect? Note that flies that have one wild-type allele and one mutant allele of the BT gene are represented by +bt, and flies that have one wild-type allele and one mutant allele of the VG gene are represented by +vg. a. all +bt +vg heterozygotes b. 1/2 bent and 1/2 vestigial flies c. all homozygous + flies d. 3/4 bent to 1/4 vestigial ratio e. 1/2 bent and vestigial to 1/2 normal

all +bt +vg heterozygotes

Assume tall (T) is completely dominant to dwarf (t) in a certain species of plant. If a homozygous dominant individual is crossed with a homozygous dwarf, the offspring will _____. a. all be intermediate in height b. all be tall c. be 1/2 tall and 1/2 dwarf d. be 3/4 tall and 1/4 dwarf e. all be short

all be tall

If you cross a plant that is homozygous for the recessive allele of a trait with a plant that is homozygous for the dominant allele of the same trait, the F1 generation will differ from the F2 in that _____. a. all of the F1 will show the dominant phenotype, whereas only half of the F2 will b. all of the F1 will show the dominant phenotype, but only three-fourths of the F2 will c. all of the F1 will show the dominant phenotype, and all of the F2 will show the recessive phenotype d. one-half of the F1 will show the dominant phenotype, and three-fourths of the F2 will e. none of the F1 will show the dominant phenotype, but one-half of the F2 will

all of the F1 will show the dominant phenotype, but only three-fourths of the F2 will

If an organism that is homozygous dominant is crossed with a heterozygote for that trait, the offspring will be _____. a. all of the dominant phenotype b. /4 of the recessive phenotype c. all homozygous dominant d. all homozygous recessive e. present in a 9:3:3:1 ratio

all of the dominant phenotype

Alternative versions of a gene are known as a. alleles b. phenotypes c. alt-genes d. dihybrids

alleles

An individual who is heterozygous at a given genetic locus for a recessively inherited disorder is known as a a. carrier b. codominant c. recessive d. dominant

carrier

A red bull is crossed with a white cow and all of the offspring are roan, an intermediate color that is caused by the presence of both red and white hairs. This is an example of genes that are _____. a. nonhomologous b. epistatic c. codominant d. polygenic e. completely dominant

codominant

If the phenotypes of both alleles are exhibited in the heterozygote, the alleles must be what type of alleles? a. dominant alleles b. codominant alleles c. incompletely dominant alleles d. recessive alleles

codominant alleles

Homologous pairs of chromosomes often _____. a. carry different genes for different traits b. differ in length c. contain different alleles d. are not both present in diploid somatic cells e. are paired up in the G2 phase of the cell cycle

contain different alleles

Phenotype a. describes the genes (or alleles of genes) carried by a particular individual. b. describes the lengths of different chromosomes. c. describes the position of the centromeres on different chromosomes. d. describes an individual's observable traits.

describes an individual's observable traits

Genotype a. describes the genes (or alleles of genes) carried by a particular individual. b. describes the lengths of different chromosomes. c. describes the position of the centromeres on different chromosomes. d. describes an individual's observable traits.

describes the genes carried by a particular individual

Physically, what are different alleles? a. Different alleles are different DNA sequences found at the same locus on sister chromatids. b. Different alleles are different particles found in gametes. c. Different alleles are different phenotypes for a particular character. d. Different alleles are different DNA sequences found at the same locus (location) on homologous chromosomes. e. None of the listed responses is correct.

different alleles are different DNA sequences found at the same locus on homologous chromosomes

Alleles are a. different versions of a gene b. the phenotypic characters expressed by different genes c. genes that segregate together d. genes that do not segregate together

different versions of a gene

What do we mean when we use the terms monohybrid cross and dihybrid cross? a. A monohybrid cross results in a 9:3:3:1 ratio whereas a dihybrid cross gives a 3:1 ratio. b. A monohybrid cross produces a single progeny, whereas a dihybrid cross produces two progeny. c. A dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid cross involves only one. d. A monohybrid cross is performed for one generation, whereas a dihybrid cross is performed for two generations.

dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid cross involves only one

An allele that is fully expressed in the phenotype of a heterozygote is a a. dominant allele b. codominant allele c. incompletely dominant allele d. recessive allele

dominant allele

The set of alleles carried by a particular organism are its a. genotype b. phenotype c. codominance d. recessiveness

genotype

What is the difference between "genotype" and "phenotype"? a. Genotype refers to which genes, or which alleles of a particular gene, are carried by an individual. Phenotype refers to the traits exhibited by an individual. b. Genotype refers to individuals that are haploid. Phenotype refers to individuals that are diploid. c. Genotype refers to individuals resulting from a monohybrid cross, whereas phenotype refers to individuals resulting from a dihybrid cross. d. Genotype refers to alleles that exhibit complete dominance, whereas phenotype refers to alleles that exhibit incomplete dominance.

genotype refers to which genes, or which alleles of a particular gene, are carried by an individual, phenotype refers to the traits exhibited by an individual

If an organism has two different alleles of a particular gene, the organism is a. heterozygous for that gene b. homozygous for that gene c. dominant for that gene d. incompletely dominant for that gene

heterozygous for that gene

A man who can roll his tongue and a woman who cannot roll her tongue have a son who can roll his tongue (R = can roll tongue; r = can't roll tongue). The son is curious about whether his father is homozygous or heterozygous for the tongue-rolling trait. Which of the following facts would allow him to know? a. His father's mother cannot roll her tongue. b. His paternal grandfather and his paternal grandmother can both roll their tongues. c. The son's sister is a tongue roller. d. The son's own daughter cannot roll her tongue. e. The son submits his own blood sample to a local genotyping lab, and they establish that he is heterozygous for the trait.

his father's mother cannot roll her tongue

If an organism has two identical alleles of a particular gene, the organism is a. heterozygous for that gene b. homozygous for that gene c. dominant for that gene d. incompletely dominant for that gene

homozygous for that gene

If a plant variety is true-breeding for a dominant trait, then _____. a. if the plant were allowed to self-pollinate, the dominant and recessive traits would consistently appear in a 3:1 ratio among the progeny b. the plant is heterozygous for the trait c. if the plant were crossed with a heterozygote, one-half of the progeny would show the dominant trait, and one-half would show the recessive trait d. if the plant were allowed to self-pollinate, all of the progeny would have the dominant trait e. the variety is unable to mutate

if the plant were allowed to self-pollinate, all of the progeny would have the dominant trait

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant characteristic. The flower color trait in radishes is an example of which of the following? a. a multiple allelic system b. sex linkage c. codominance d. incomplete dominance e. full dominance

incomplete dominance

If the phenotype of a heterozygote is intermediate between the phenotypes of individuals homozygous for either allele, the alleles carried by that heterozygote must be what type of alleles? a. dominant alleles b. codominant alleles c. incompletely dominant alleles d. recessive alleles

incompletely dominant alleles

Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties? a. No genes interacted to produce the parental phenotype. b. Each allele affected phenotypic expression. c. The traits blended together during fertilization. d. One phenotype was completely dominant over another.

one phenotype was completely dominant over another

The observable physical and physiological traits of an organism, which are determined by its genetic makeup, are its a. genotype b. phenotype c. codominance d. recessiveness

phenotype

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant characteristic. If true-breeding red long radishes are crossed with true-breeding white oval radishes, the F1 will be expected to be which of the following? a. red and long b. red and oval c. white and long d. purple and long e. purple and oval

purple and long

An allele whose phenotypic effect is not observed in a heterozygote is a a. dominant allele b. codominant allele c. incompletely dominant allele d. recessive allele

recessive allele

It is far more common to find human genetic disease caused by _____ alleles than by _____ alleles because _____. a. dominant ... recessive ... dominant alleles have an evolutionary advantage over recessive alleles b. dominant ... recessive ... dominant alleles became dominant because they aid the survival of the organism carrying them c. recessive ... dominant ... harmful recessive alleles can survive in the heterozygote without any selection pressure against them d. recessive ... dominant ... even when homozygous, recessive alleles usually do not cause as much damage as dominant alleles e. None of the listed responses is correct.

recessive, dominant, harmful recessive alleles can survive in the heterozygote without any selection pressure against them

In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white? a. red × white b. roan × roan c. white × roan d. red × roan

roan x roan

Cystic fibrosis, which is usually lethal before the age of reproduction, is a homozygous recessive trait. Why do cases continue to arise, even though people with the disease rarely live to reproduce? a. New mutations continually introduce this harmful condition into the population. b. The harmful allele "hides" within heterozygous individuals, and one-fourth of the offspring of two heterozygotes would be afflicted. c. Mosquitoes can transfer the disease from person to person. d. People continue to make inappropriate lifestyle choices. e. None of the listed responses is correct.

the harmful allele hides within heterozygous individuals and one-fourth of the offspring of two heterozygotes would be afflicted

Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. What does this suggest? a. that the parents were true-breeding for contrasting traits b. that the trait shows incomplete dominance c. that a blending of traits has occurred d. that the parents were both heterozygous for a single trait

the parents were both heterozygous for a single trait

Pea plants are tall if they have the genotype TT or Tt, and they are short if they have genotype tt. A tall plant is mated with a short plant. Which outcome below would indicate that the tall parent plant was heterozygous? a. All of the offspring are short. b. All of the offspring are tall. c. The ratio of tall offspring to short offspring is 3:1. d. The ratio of tall offspring to short offspring is 1:1. e. There is not enough information to answer the question.

the ratio of tall offspring to short offspring is 1:1

Why did Mendel continue some of his experiments to the F2 or F3 generation? a. to obtain a larger number of offspring on which to base statistics b. to observe whether or not a recessive trait would reappear c. to observe whether or not the dominant trait would reappear d. to distinguish which alleles were segregating e. to be able to describe the frequency of recombination

to observe whether or not a recessive trait would reappear

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants? a. There is considerable genetic variation in garden peas. b. Traits are inherited in discrete units, and are not the results of "blending." c. Recessive genes occur more frequently in the F1 generation than do dominant ones. d. Genes are composed of DNA.

traits are inherited in discrete units and are not the results of blending

Mendel accounted for the observation that traits which had disappeared in the F1 generation reappeared in the F2 generation by proposing that a. new mutations were frequently generated in the F2 progeny, "reinventing" traits that had been lost in the F1. b. the mechanism controlling the appearance of traits was different between the F1 and the F2 plants. c. traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1. d. the traits were lost in the F1 due to dominance of the parental traits. e. members of the F1 generation had only one allele for each trait, but members of the F2 had two alleles for each trait.

traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1